This relates to an instrument for use by a surgeon to place and/or remove a stent within and along an axis aligned with a patient""s lumen. More particularly, the instrument can be loaded with a stent by the practitioner, is reusable because it is easily assembled and disassembled for cleaning, and sterilization.
Tubular prostheses for transluminal implantation in body canals, for example urethra or ureters, for the purpose of repair or dilation are known. These prostheses, referred to herein as stents, may be generally tubular elements. Stents are self expanding or are balloon expandable radially within a lumen to open therethrough a passage, herein all types of stents will be referred to as expanding stents.
A typical self-expanding stent is disclosed in U.S. Pat. No. 4,655,771, Which stent has a radially and axially flexible, elastic tubular body of a predetermined diameter that is variable under axial movement of ends of the body relative to each other. That stent has of a plurality of individually rigid but flexible and elastic thread elements defining a radially self-expanding helix. The disclosure in U.S. Pat. No. 4,655,771 is made is a part hereof and incorporated herein by reference.
Placement of the stent according to U.S. Pat. No. 4,665,771 in a body vessel is achieved by a device having a piston to push the stent or a latch to hook the stent and push or pull it into position.
U.S. Pat. No. 4,990,151 has an instrument for the implantation or extraction of a stent. The instrument has a plurality of internally held spring members that are released by withdrawal of an over tube. The members thus engage the inside of the urethra to expand the lumen so the spring members can be advanced over the stent and caused to engage the outside thereof whereupon the over tube is positioned to keep the members engaged. While this instrument comes apart for sterilization and reuse, it is not adjustable for different size stents and was made to use for explantation.
U.S. Pat. No. 4,768,507 has a mandrel for carrying a spring helix inside a tube and is delivered by removing the tube so the helix spring can unwind and expand. It is shown as a disposable instrument.
U.S. Pat. No. 5,026,377 describes and claims in combination, a self-expanding braided stent as in ""771 and an instrument for the deployment or retraction in a body canal of the stent. The instrument has an elongated tubular outer sleeve with proximal and distal ends, an elongated core in the sleeve is movable relative thereto so the core which is longer than the sleeve includes a grip member at or near its distal end. The grip member is on the core to: (I) releasably hold the self expanding stent within the outer sleeve, (ii) deploy the stent beyond the distal end of the outer sleeve when the outer sleeve is moved in a backward direction relative to the core and (iii) retract the stent back within said outer sleeve when the core is pulled in a backward direction relative to the outer sleeve.
European Patent Number EP 0 518 838 A1 has a transluminal implantation device for an implantation of substantially tubular, radially expandable stent. The device has a central tube or shaft surrounded by an outer tube axially displaceable relative said central tube or shaft, the radial dimensions of the tubes or tube and shaft forming an annular space therebetween for holding the stent in an unexpanded state. The held stent can be axial displaced from the outer tube relative to said central tube or shaft at a distal end thereof. There is an undercut groove forming a circumferential flange wherein the proximal end of the stent rests until release with rearward displacement of the outer tube.
It has now been found that a reusable deployment instrument for implanting a variety of stent designs and configurations may be needed to reduce the cost and expense of medical care. The need to sterilize and adjust the instrument has not been solved by the disposable deployment devices available. Moreover it is not a simple matter to revise such disposable tools to be used for more than one time. Manufactures of those disposable devices strive to make such tools difficult or impossible to reuse.
This invention relates to a reusable instrument for the placement of a stent in a body canal, and means for positioning and releasing the stent.
An instrument for use by a surgeon to place within and remove from a patient""s lumen a stent aligned along an axis is preferably reusable in that it can be disassembled for cleaning and may be reloaded with a new stent. The instrument is also adjustable for stents of different sizes. A thumb loop for manipulation by a surgeon may have an open center into which the surgeon""s thumb may fit when it is normal to the axis. An arm extending tangentially from the thumb loop is preferably in a plane with the axis. The arm may perhaps have at least one bore in alignment with the axis. A tab extends from the arm along the axis and from the thumb loop so the arm, tab and thumb loop reside substantially in the plane with one another and the axis.
A finger ring for manipulation by a surgeon could be centrally open to receive the surgeon""s finger. A limb extends tangentially from the finger ring and is preferably attached thereto. The limb can include an axially aligned hole so the hole, finger ring and the limb may be positioned in the plane with the axis. A front bracket extends from the tab over and in front of the limb. A tube to support the stent could be located for extending therefrom. The tube may be positioned for coaxial deposition about the axis, into the bore and the hole, the tube for locating the finger ring forward of the thumb loop. The location of the tube is preferably for ergonomic use by the surgeon in a sliding action of the finger ring relative to the tube when guided along axis.
A stent end can be on the tube opposite where the tube fits bore for gripping the stent in the sheath for delivery. A sheath might be for sliding along the stent end on the tube when the sheath extends from the hole along the axis and toward the stent end. The sheath is most preferably coaxially disposed about the tube. A cavity in the sheath beyond the stent end on the tube may be included for accommodating the stent being carried along the axis cantilever from the stent end on the tube. A shaft positioned in the plane could be attached to the front bracket. The shaft may be generally parallel to the axis so the shaft conjugates with the limb and arm to prevent relative rotary motion between them with respect to the axis.
An axial control preferably fits within the arm for selective movement by the surgeon relative to the shaft. The axial control is preferred for adjusting the axial position of the shaft relative to the arm. Thus the axial control can be used for setting the axial position of the shaft with respect to the arm to thereby adjust the instrument for stents of various lengths. A latch on the front bracket may be to secure the relative axial positions of the limb and the front bracket. The latch can be used to selectively permit the surgeon to move the sheath relative to the tube for loading and thereafter delivering the stent. A catch on the tab may be included to prevent complete release of the stent from the tube without the prior manual release of the catch thus permitting the finger ring to fully approach the thumb loop.
At least one grip can be carried between the stent and the stent end for engaging the stent reduced to a diameter to fit within the cavity before and during placement and/or removal from the patient""s lumen. The at least one grip is most preferably operatively mounted in the sheath near the stent end for axially locating precisely the stent within the patient""s lumen for release. The axial control, the latch and the catch are in the preferred embodiment all positioned relative to the shaft and the tab and the front bracket, respectively so the instrument may either be disassembled for cleaning and sterilization or assembled and adjusted to a particular stent length. The latch might include a spring loaded key on the front bracket and the catch can have a spring loaded key on the tab. Each spring loaded key is most preferably positioned to cooperatively engage a receiving way atop the limb for limiting the axial movement of the finger ring relative to the thumb loop.
The axial control might include a lock for transverse movement by the surgeon relative to the arm. The shaft may have settings for cooperative engagement with the lock to define preset adjustment locations for accommodating stents of various lengths. A support might be fit coaxially over and about the sheath. The support preferably extends along the sheath from the front bracket so that axial movement of the sheath may be independent of the support. A flange can be on the support for abutting the front bracket and a tang on the abutted flange resiliently engages the front bracket to restrain axial movement of the flange away from the front bracket. The axial control may alternately include a pinion carried on the arm for rotary movement by the surgeon relative to a rack on the shaft for setting the adjustment locations of the tube relative to the sheath for accommodating stents of various lengths.
An adapter preferably abuts the arm and extends away from the patient and toward the surgeon. The adapter can be shaped for permitting sliding engagement relative to the shaft. An extension may be fit within the arm and over the shaft in parallel relation to the adapter. The extension might be for supporting the sliding engagement of the adapter with the arm along the shaft when directed away from the stent end. The latch and the catch preferably hold the limb from axial motion toward the surgeon but may be manually released for such axial movement and automatically permit axial limb motion away from the surgeon.
A method of assembling and disassembling an instrument for use by a surgeon to place a stent within a patient""s lumen has operating steps. Extending a tube to support the stent in coaxial disposition about the axis, into the bore and the hole is a step of the preferred method. The method may have the step of locating the finger ring on the tube forward of the thumb loop for ergonomic use by the surgeon in a sliding action of the finger ring relative to the tube when guided along axis. Sliding a sheath extending from the hole and coaxially disposed about the tube may be a step. The method step of accommodating the stent in a cavity within the sheath and along the axis can be included. Conjugating a shaft positioned attached to the front bracket and parallel to the axis with the limb and the arm to prevent relative rotary motion between them with respect to the axis might be followed. The method could include moving an axial control fit within the arm and adjusting the axial position of the shaft relative to the arm for setting the axial position of the shaft with respect to the arm to thereby changing the instrument for stents of various lengths. The method preferably has the step of securing the relative axial positions of the limb and the front bracket with a latch on the front bracket and selectively permitting the surgeon to move the tube relative to the sheath for loading and thereafter delivering the stent. The step of preventing complete release of the stent from the tube without the prior manual release of a catch on the tab and thereby permitting the finger ring to fully approach the thumb loop is in the method.
The step of engaging with a grip the stent reduced to a diameter to fit within the cavity before and during placement and/or removal from the patient""s lumen is part of the method. The method step of disassembling via the latch and the catch the instrument for sterilization is preferred. The method may include the step of adjusting the shaft to a particular stent length with the axial control. The step of cooperatively engaging a receiving way atop the limb for limiting the axial movement of the finger ring relative to the thumb loop with a spring loaded key on the front bracket and with a spring loaded key on the tab can be performed. The method step of moving a lock of the axial control transversely relative to the arm and the shaft to define preset adjustment locations for accommodating stents of various lengths is preferred. The step of the method of extending a support fitted coaxially over and about the sheath is followed.